I tried to use groupmems command, but failed.
I checked in Ubuntu, it works after I installed libvshadow-utils. In Rocky, it works after I installed shadow-utils.
In openSUSE, I tried to install libvshadow-tools, but the command groupmems still not found.
Please advise which is the right package to install groupmems? I could not get answer from internet.
Hi and welcome to the Forum 
That utility is not used in openSUSE and deleted from the package shadow.
See line 170 on: https://build.opensuse.org/package/view_file/Base:System/shadow/shadow.spec?expand=1